Sunlight and conventional indoor lighting comprises energy in the visible range and in the ultraviolet (UV) range. The ultraviolet component, especially radiation ranging from 200 nm to 400 nm, is primarily responsible for the degradation of organic matter, including polymeric products and food products. Such food products are typically contained in packaging composed of one or more polymeric components. Thus, it is desirable that the polymeric packaging materials minimize, as much as possible, the transmission of ultraviolet light. Polyester resins are widely used in packaging materials due to their excellent clarity and transparency. Polyesters are subject to degradation by ultraviolet light and will transmit UV light. Ultraviolet absorbers are added to polyester formulations to increase the resistance of the final resin product to UV degradation, and to decrease the transmission of ultraviolet light through the final product but maintain the transmission of visible light.
As the use of polyester packaging, and in particular, PET (polyethylene terephthalate), continues to grow, more and more foods and drinks are now being packaged in polyester-based resins. As mentioned above, some of the ingredients in food and drink items are susceptible to degradation by UV light from the sun and from grocery/convenience store lighting. Such degradation can result in changes in color, flavor or nutritional value of the contents of the packaging. Polyethylene terephthalate with no UV absorber will protect against UV light by providing around 10% transmission at about 320 nm wavelength.
In the last few years, chemical additive suppliers and PET producers have begun selling products that block UV light, and reduce the harmful exposure that degrades PET containers, and the contents within these containers. These additives can be incorporated at an injection molding step. PET producers are also incorporating these same commercial additives or proprietary formulations directly into their processes. This invention relates to formulations that provide end products that significantly reduce UV transmission therethrough, and more reliably withstand the effect of UV radiation without significant degradation or deterioration. These formulations or compositions also offer an alternative supply option to those that wish to convert to the use of PET containers from other conventionally UV resistant polymer based containers.